Fix WeFax auto-scheduler: prevent silent timer death and connect SSE

Timer threads now log on fire and catch all exceptions so scheduled
captures never die silently.  Frontend connects SSE when the scheduler
is enabled (not only on manual Start) and polls /wefax/status every 10s
as a fallback so the UI stays in sync with auto-fired captures.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

utils/wefax_scheduler.py

@@ -296,6 +296,11 @@ class WeFaxScheduler:
                 sb._timer.daemon = True
                 sb._timer.start()
 
+                logger.info(
+                    "Scheduled capture: %s at %s UTC (fires in %.0fs)",
+                    content, utc_time, delay,
+                )
+
                 self._broadcasts.append(sb)
 
             logger.info(
@@ -314,6 +319,24 @@ class WeFaxScheduler:
         self._refresh_timer.start()
 
     def _execute_capture(self, sb: ScheduledBroadcast) -> None:
+        """Execute capture for a scheduled broadcast (with error guard)."""
+        logger.info("Timer fired for broadcast: %s at %s", sb.content, sb.utc_time)
+        try:
+            self._execute_capture_inner(sb)
+        except Exception:
+            logger.exception(
+                "Unhandled exception in scheduled capture: %s at %s",
+                sb.content, sb.utc_time,
+            )
+            sb.status = 'skipped'
+            self._emit_event({
+                'type': 'schedule_capture_skipped',
+                'broadcast': sb.to_dict(),
+                'reason': 'error',
+                'detail': 'internal error — see server logs',
+            })
+
+    def _execute_capture_inner(self, sb: ScheduledBroadcast) -> None:
         """Execute capture for a scheduled broadcast."""
         if not self._enabled or sb.status != 'scheduled':
             return